1. Field of the Invention
This invention relates generally to imaging of the eye, for example spectral, polarization and/or three-dimensional imaging of the retina.
2. Description of the Related Art
Specialized cameras are used by optometrists, ophthalmologists, and other medical professionals to record images of the interior surface of the eye. During a routine physical examination, a handheld ophthalmoscope is often used to quickly view the fundus. Additional camera attachments can be used to record digital images from handheld ophthalmoscopes, allowing acquired images to be saved, manipulated, and reevaluated at future examinations. However, these images are limited by brightness, field-of-view, motion blur, and resolution, which restrict their diagnostic abilities for many diseases.
More complex imaging systems (e.g., fundus camera) can provide the clinician with better image quality, leading to more accurate diagnosis, screening, and monitoring treatment of eye pathologies. Conventional fundus cameras provide an image of the fundus with 2 to 5× magnification, with a field-of-view of 15 to 140 degrees. The device typically incorporates specialized illumination optics to shine light onto the interior surface of the eye. An eyepiece can be used to allow the clinician to view the interior of the eye. An electronic sensor can be used for digital acquisition of images. During an examination, the medical professional inspects the interior of the eye for abnormalities such as retinal tearing, thinning, unhealthy vasculature, opacity, occlusions, enlarged or reduced anatomy, and discoloration.
However, conventional fundus cameras have several drawbacks. First, in many cases, absolute measurements of anatomical features would be beneficial to determine the type and severity of disease. However, conventional fundus cameras produce a two-dimensional image of the three-dimensional eye. This makes it difficult or impossible to assess absolute measurements of area, depth or volume for the three-dimensional anatomy. Second, in many cases, spectral, polarization or other imaging modalities would also be beneficial. Conventional fundus cameras typically might capture different filtered images sequentially in time. Snapshots taken at different times must then be registered with each other. However, since the eye is constantly moving, this introduces a registration problem. In a different approach, it is possible to modify conventional fundus cameras to capture multiple filtered images in a single snapshot, for example by using multiple sensor arrays. However, this makes the camera more complex and expensive, and the multiple optical paths must be aligned to each other to ensure correct image registration.
Therefore, there exists a need for improved imaging systems to allow the simultaneous capture of three-dimensional, spectral, polarization and other modality images.